The present invention relates to a microwave receiver for counterclockwise and clockwise circularly polarized microwave signals, the receiver comprising a receiving antenna with a feeder waveguide, a polarization converter, a polarization filter and circuit for converting the microwave signals of both polarization directions from the high frequency plane to the intermediate frequency plane.
Conventional microwave receivers generally are designed in the following manner. Usually, the antenna is followed by the polarization converter and the polarization filter, both in the form of hollow waveguides. Each one of the two arms associated with the different polarization directions of the polarization filter is followed by a receiving circuit branch including a frequency converter. Each frequency converter is preceded by a bandpass filter in the form of a hollow waveguide which is connected to the polarization filter and to a low-noise preamplifier. Finally, the frequency converter is followed by an image-frequency suppression filter and an intermediate frequency amplifier. If the preamplifier, frequency converter, image-frequency suppression filter and intermediate frequency amplifier are provided in the form of an integrated microwave circuit, transitions are required from the hollow waveguide bandpass filters to microstriplines.
Such a conventional microwave receiver is not suited for use in a television satellite home receiving system, which is of particular interest here, since the above-described conventional receiver has a much too complicated, and therefore too expensive, structure. Moreover, it is not designed to have the smallest possible spatial dimensions.